Storm Prediction Center Day 4-8 Severe Weather Outlook Page (2024)

SPC on Facebook

@NWSSPC

NCEP Quarterly Newsletter

 ZCZC SPCSWOD48 ALL ACUS48 KWNS 030900 SPC AC 030900 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Fri May 03 2024 Valid 061200Z - 111200Z ...SEVERE WEATHER OUTBREAK POSSIBLE ON D4/MON... ...DISCUSSION... A multi-day period of organized severe thunderstorm potential appears likely across parts of the central to eastern CONUS next week, beginning on Day 4/Monday across the Plains, and continuing through at least Day 6/Wednesday. ...Day 4/Monday... A negatively tilted upper trough will eject northeastward over the northern/central Plains on Monday. Pronounced low-level mass response will encourage rich low-level moisture to advect northward over the southern/central Plains, as a surface low rapidly deepens over the northern High Plains. Strong deep-layer shear and at least moderate instability are expected to be in place ahead of a surface dryline extending across the southern/central Plains. Thunderstorms will likely erupt along the length of the dryline by late Monday afternoon from southern NE into central KS and north-central OK. Supercells are likely to be the dominant mode initially given the strength of the deep-layer shear. Both very large hail and tornadoes will be possible with these supercells as they spread eastward across the southern/central Plains through Monday evening. With a southerly low-level jet forecast to strengthen to at least 50-60 kt Saturday evening, a corresponding rapid increase in low-level shear will likely support a continued threat for tornadoes with any discrete convection. Some of these tornadoes could be strong. The severe threat will likely continue Monday night with eastward extent across the Plains, before convection possibly weakens some towards early Tuesday morning. Given increased confidence in high-end severe potential, a 30% severe area has been introduced from parts of southern NE into central KS and north-central OK. ...Day 5/Tuesday... The large-scale upper trough/low is forecast to gradually occlude over the northern Plains on Tuesday. But, an enhanced mid-level jet and embedded vorticity maximum will likely overspread parts of the Upper Midwest, mid MS Valley, and OH Valley through Tuesday evening. An expansive warm sector will likely be in place across these regions ahead of a surface cold front/dryline. Robust convection should develop along/ahead of these boundaries through the day. Sufficient instability and deep-layer shear will likely exist to support organized severe thunderstorms, including supercells posing a threat for all severe hazards. The northeastward extent of the warm sector remains somewhat uncertain into the OH Valley. Still, some severe risk will probably persist into Tuesday evening/night with eastward extent across the mid MS Valley and lower OH Valley/Midwest. Expansion of the 15% severe area may be needed in later outlooks, pending better model agreement and increased confidence in the eastward extent of rich low-level moisture and related instability. ...Day 6/Wednesday... The upper trough/low should gradually evolve eastward across the northern Plains on Wednesday. While there are still some differences in model guidance regarding the evolution of an embedded shortwave trough, there appears to be enough agreement in the synoptic pattern to include a 15% severe delineation for Wednesday for parts of the southern Plains into the ArkLaTex/Ozarks and towards the mid MS Valley. Across these areas, strong instability is forecast to develop east of a front/dryline. With enhanced mid-level flow persisting with a westerly mid/upper-level jet, organized severe thunderstorms should once again develop Wednesday afternoon. Supercells posing a threat for all severe hazards may occur. The northern/eastern extent of the severe threat is unclear, as the convection from Tuesday may tend to limit better low-level moisture return into the OH/TN Valleys. Depending on model trends over the next few days, the 15% severe area may need to be expanded to include these regions. ...Day 7/Thursday and Day 8/Friday... Some severe threat may continue on Thursday from parts of TX into the lower MS Valley/Southeast, generally along/south of a front and any convection that develops Wednesday. Too much uncertainty currently exists to include a 15% severe area at this time, but trends will be monitored. A severe risk also appears possible next Friday across the same general regions, but confidence in the placement of the front and convection is even lower than Thursday. ..Gleason.. 05/03/2024 CLICK TO GET WUUS48 PTSD48 PRODUCT